MCU and relay driver to control output from higher voltage battery. Simulation made to show basic of campervan power supply idea. 3.3v circuit demonstrate ESP32-S3 side, logic output ULN2803 driver, 12v leisure battery in van, bulbs are just random picked output loads.
Note 1: when switch is OFF on 3.3v logic should go 0 but can't simulate it (or don't know how - yet).
